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iron overload (iron poisoning)

Etiology: 1) transfusion associated a) congenital hemolytic anemia b) long-standing aplastic anemia 2) surreptitious ingestion Pathology: 1) iron-induced organ toxicity may be seen when > 500 mL/kg of total packed erythrocytes are admministered (1 unit is about 300 mL with hematocrit of 70-80%) 2) endocrine disturbances, including diabetes mellitus 3) cirrhosis 4) growth retardation 5) cardiac toxicity (may be fatal) Genetics: - mutations in SLC11A2 are associated with progressive liver iron overload & normal to moderately elevated serum ferritin levels Clinical manifestations: - hemorrhagic GI symptoms within 6 hours of ingestion - vomiting, diarrhea - symptoms may improve 6-12 hours after ingestion with supportive care - systemic toxicity may occur 12-24 hours after ingestion Laboratory: - iron studies (% transferrin saturation) Complications: - multiorgan failure - metabolic acidosis - liver injury - hypovolemia or shock - altered mental status - lethargy or coma - seizures Management: 1) transfusion-related iron overload: - iron chelation therapy (deferoxamine) when transferrin becomes fully saturated or evidence of iron-induced tissue damage [1] - therapeutic phlebotomy contraindicated patient is anemic - deferiprone or deferasirox oral chelating agents may be more convenient than deferoxamine infusion 2) ingestion of iron: (also see poisoning) a) ingestion of > 20 mg/kg of elemental iron generally needs active management b) gastric decontamination 1] ipecac a] within 30-45 minutes of ingestion (not effective) [2] b] contraindications include: ingestion of caustic agents, hydrocarbons, drugs known to cause abrupt loss of consciousness or seizures, foreign bodies, non-toxic substances; unconscious patients, patients with seizures, inability to protect airway (intubated patients) [2]; patients with intentional ingestion 2] gastric lavage a] performed prior to administration of charcoal b] activated charcoal not recommended [2] c] 34-40 French orogastric tube (adults) d] 150-200 mL aliquots of warm water or normal saline e] 5-10 liters total c) whole bowel irrigation 1] polyethylene glycol-electrolyte lavage solution 2] dosage: a] 2 liters/hour for 5 hours (adults) b] 500 mL/hr (children) 3] most effective means of GI decontamination d) iron chelation therapy (deferoxamine) - if systemic manifestations or serum iron > 500 ug/dL - ingestion of > 20 mg/kg of elemental iron [2] e) GI decontamination not recommented if pills have already been absorbed or if liquid iron solutions were ingested [2] 3) also see hemochromatosis 4) AVOID vitamin C supplements

Related

hemochromatosis iron [Fe]

General

hematologic disease (blood disorder, blood dyscrasia) toxicity; poisoning; overdose

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, 16, 17, 18. American College of Physicians, Philadelphia 1998, 2009, 2012, 2015, 2018.
  2. NEJM Knowledge+ Question of the Week. Aug 21, 2018 https://knowledgeplus.nejm.org/question-of-week/4149/
  3. Madiwale T, Liebelt E. Iron: not a benign therapeutic drug. Curr Opin Pediatr 2006 Apr 8; 18:17 PMID: 1660149
  4. Chang TP, Rangan C. Iron poisoning: a literature-based review of epidemiology, diagnosis, and management. Pediatr Emerg Care 2011 Oct; 27:978 PMID: 21975503
  5. Manoguerra AS, Erdman AR, Booze LL et al. Iron ingestion: an evidence-based consensus guideline for out-of-hospital management. Clin Toxicol (Phila) 2005; 43:553 PMID: 16255338